On Tue, 10 May 2016, Dave Airlie <airlied at gmail.com> wrote:
> From: Dave Airlie <airlied at redhat.com>
>
> We need to use this for validating modeline additions.
>
> Signed-off-by: Dave Airlie <airlied at redhat.com>
> ---
> drivers/gpu/drm/drm_edid.c | 44 ++++++++++++++++++++++++++------------------
> 1 file changed, 26 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> index 3cf17a3..73d4218 100644
> --- a/drivers/gpu/drm/drm_edid.c
> +++ b/drivers/gpu/drm/drm_edid.c
> @@ -3901,6 +3901,29 @@ static void drm_add_display_info(struct edid *edid,
> info->color_formats |= DRM_COLOR_FORMAT_YCRCB422;
> }
>
> +static int validate_displayid(u8 *displayid, int length, int idx)
Bikeshed, (u8 *displayid, int idx, int length) would feel like a more
natural order to me.
> +{
> + int i;
> + u8 csum = 0;
> + struct displayid_hdr *base;
> +
> + base = (struct displayid_hdr *)&displayid[idx];
> +
> + DRM_DEBUG_KMS("base revision 0x%x, length %d, %d %d\n",
> + base->rev, base->bytes, base->prod_id, base->ext_count);
> +
I guess to be pedantic we should check idx + sizeof(struct
displayid_hdr) <= length before looking at base. This patch is about
abstracting the thing, so should be a separate patch anyway.
Other than the bikeshed,
Reviewed-by: Jani Nikula <jani.nikula at intel.com>
> + if (base->bytes + 5 > length - idx)
> + return -EINVAL;
> + for (i = idx; i <= base->bytes + 5; i++) {
> + csum += displayid[i];
> + }
> + if (csum) {
> + DRM_ERROR("DisplayID checksum invalid, remainder is %d\n",
> csum);
> + return -EINVAL;
> + }
> + return 0;
> +}
> +
> /**
> * drm_add_edid_modes - add modes from EDID data, if available
> * @connector: connector we're probing
> @@ -4212,30 +4235,15 @@ static int drm_parse_display_id(struct drm_connector
> *connector,
> {
> /* if this is an EDID extension the first byte will be 0x70 */
> int idx = 0;
> - struct displayid_hdr *base;
> struct displayid_block *block;
> - u8 csum = 0;
> - int i;
> int ret;
>
> if (is_edid_extension)
> idx = 1;
>
> - base = (struct displayid_hdr *)&displayid[idx];
> -
> - DRM_DEBUG_KMS("base revision 0x%x, length %d, %d %d\n",
> - base->rev, base->bytes, base->prod_id, base->ext_count);
> -
> - if (base->bytes + 5 > length - idx)
> - return -EINVAL;
> -
> - for (i = idx; i <= base->bytes + 5; i++) {
> - csum += displayid[i];
> - }
> - if (csum) {
> - DRM_ERROR("DisplayID checksum invalid, remainder is %d\n",
> csum);
> - return -EINVAL;
> - }
> + ret = validate_displayid(displayid, length, idx);
> + if (ret)
> + return ret;
>
> idx += sizeof(struct displayid_hdr);
> while (block = (struct displayid_block *)&displayid[idx],
--
Jani Nikula, Intel Open Source Technology Center
